The permanent alteration of the colour of keratinous fibers, in particular human hair, by the application of hair dyes is well known. In order to provide the consumer with the hair colour and the intensity of the colour desired, very complex chemical processes are utilized. Permanent hair colouring formulations typically comprise oxidative hair dye precursors, which can diffuse into the hair through the cuticle and into the cortex where they can then react with each other and suitable oxidizing agents to form the end dye molecule. Due to the larger size of these resultant molecules they are unable to readily diffuse out of the hair during subsequent washing with water and/or detergent; hence delivering a consumer-desired permanency of colour. This reaction typically takes place at pH from about 8.5 to about 10.5 (approximately pH 10) in the presence of an alkalizing agent and an oxidizing agent.
Despite the fact that commercial hair colouring products have been available for many years, the products still exhibit a number of consumer-related deficiencies.
Typically, permanent hair dye products will contain an alkali, typically a source of ammonia. This serves the purpose of swelling the hair allowing the entry of the dye precursor molecules into the hair and also improves the lightening effect of the oxidizing agent, which is typically hydrogen peroxide. Ammonia shows the best hair colouring and/or bleaching performance as well as hair damage profile, versus alternative alkalizing agents. However, ammonia is also volatile and its associated odour is extremely unpleasant to the consumers of such products, particularly as these hair colouring and/or bleaching products are used in close proximity to the nasal region. Hence, it would be highly desirable to provide an oxidative hair colouring and/or bleaching composition, and kit thereof, which delivers the consumer required lightening level and colour but which has reduced or eliminated the detectable ammonia odour.
A number of attempts have been described in the literature to address the above identified improvement areas. For example, it has been described hair colouring and/or bleaching compositions comprising carbonate and/or carbamate compounds. It has also been described hair colouring and/or bleaching compositions comprising an alkalizing agent, alternative to ammonia and its salts, such as monoethanolamine. It has also been described compounds blocking and/or antagonizing the odour of ammonia. Furthermore, compositions comprising a certain level of fatty compound have also been developed. However these previous attempts have not proven fully satisfactory vis-à-vis further criteria, as they may exhibit a limited hair colouring and/or bleaching performance including limited colour delivery, uptake and/or durability; significant damages to the hair including brittle fibre formation and/or impart a greasy feeling to hair when the composition is applied onto hair. In some embodiments, the use of fatty compounds in the compositions may have further disadvantages, e.g. the process for making the compositions may be more complex and the compositions may have a weaker stability at high temperatures.
Compositions with reduced ammonia smell have been disclosed in WO 2014/090645 A2, US 2014/0165299 A1, US 2014/0165300 A1 and WO 2015/018412 A2.
However, there is still the need for providing a composition comprising ammonia and/or its salts thereof, which releases a reduced or no odour, especially upon application onto hair. There is also the need for providing a composition comprising ammonia and/or its salts thereof, which releases a reduced or no odour, while providing superior hair treatment performance. There is also the need for providing a composition comprising ammonia and/or its salts thereof, releasing a reduced or no odour, without imparting significant damages onto the hair fibers. There is also the need for providing a composition comprising ammonia and/or its salts thereof releasing a reduced or no odour, without imparting a greasy feeling to hair. Finally, there is also the need for providing a composition comprising ammonia and/or its salts thereof releasing a reduced or no odour which is easy to make and is characterized by a good stability at high temperatures.